WO2018047444A1 - 熱間圧延用ロール外層材および熱間圧延用複合ロール - Google Patents

熱間圧延用ロール外層材および熱間圧延用複合ロール Download PDF

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WO2018047444A1
WO2018047444A1 PCT/JP2017/023663 JP2017023663W WO2018047444A1 WO 2018047444 A1 WO2018047444 A1 WO 2018047444A1 JP 2017023663 W JP2017023663 W JP 2017023663W WO 2018047444 A1 WO2018047444 A1 WO 2018047444A1
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Prior art keywords
roll
outer layer
hot rolling
rolling
layer material
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PCT/JP2017/023663
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English (en)
French (fr)
Japanese (ja)
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直道 岩田
鈴木　健史
祥一 松村
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Ｊｆｅスチール株式会社
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Application filed by Ｊｆｅスチール株式会社 filed Critical Ｊｆｅスチール株式会社
Priority to BR112019003360A priority Critical patent/BR112019003360A2/pt
Priority to EP17848389.7A priority patent/EP3479915B1/en
Priority to KR1020197004864A priority patent/KR102234330B1/ko
Priority to CN201780050783.6A priority patent/CN109641250B/zh
Priority to JP2017552525A priority patent/JP6292362B1/ja
Publication of WO2018047444A1 publication Critical patent/WO2018047444A1/ja

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B27/00—Rolls, roll alloys or roll fabrication; Lubricating, cooling or heating rolls while in use
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D19/00—Casting in, on, or around objects which form part of the product
    • B22D19/08—Casting in, on, or around objects which form part of the product for building-up linings or coverings, e.g. of anti-frictional metal
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D13/00—Centrifugal casting; Casting by using centrifugal force
    • B22D13/02—Centrifugal casting; Casting by using centrifugal force of elongated solid or hollow bodies, e.g. pipes, in moulds rotating around their longitudinal axis
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D19/00—Casting in, on, or around objects which form part of the product
    • B22D19/16—Casting in, on, or around objects which form part of the product for making compound objects cast of two or more different metals, e.g. for making rolls for rolling mills
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B27/00—Rolls, roll alloys or roll fabrication; Lubricating, cooling or heating rolls while in use
    • B21B27/02—Shape or construction of rolls
    • B21B27/03—Sleeved rolls
    • B21B27/032—Rolls for sheets or strips
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D5/00—Heat treatments of cast-iron
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/38—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for roll bodies
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C37/00—Cast-iron alloys

Definitions

  • the present invention relates to a composite roll for hot rolling, and more particularly to a roll outer layer material for hot rolling and a composite roll for hot rolling suitable for use in a hot rolling finish mill of a steel plate.
  • Patent Document 1 discloses that C: 1.5 to 3.5%, Ni: 5.5% or less, Cr: 5.5 to 12.0%, Mo : 2.0 to 8.0%, V: 3.0 to 10.0%, Nb: 0.5 to 7.0%, and Nb and V include Nb, V and C content.
  • a rolling roll outer layer material that satisfies a specific relationship and further contains a ratio of Nb and V within a specific range has been proposed. Thereby, even if the centrifugal casting method is applied, segregation of hard carbides in the outer layer material is suppressed, and the outer layer material of the roll for rolling is excellent in wear resistance and crack resistance.
  • Patent Document 2 C: 1.5 to 3.5%, Cr: 5.5 to 12.0%, Mo: 2.0 to 8.0%, V: 3.0 to 10.0 %, Nb: 0.5 to 7.0%, and Nb and V, the contents of Nb, V and C satisfy a specific relationship, and the ratio of Nb to V is within a specific range
  • a roll outer layer material for rolling containing so as to have been proposed.
  • Patent Document 3 discloses that C: 2.2 to 2.6%, Cr: 5.0 to 8.0%, Mo: 4.4 to 6.0%, V: 5 Adjust the C, Mo, V, and Nb contents so that Mo + V and C-0.24V-0.13Nb are within the specified range.
  • the present invention has been made in view of the above circumstances, and while ensuring the wear resistance, reducing the pit-like wrinkles on the roll surface, the roll outer layer material for hot rolling and the hot It aims at providing the composite roll for rolling.
  • the present inventors investigated in detail the location of the occurrence of pit-like wrinkles formed on the surface of the hot rolling roll.
  • the pit-shaped soot is formed by cracks generated from eutectic carbides (mainly M 2 C, M 6 C, M 7 C 3 and M 23 C 6 carbides) propagating through the base structure. It was clarified that the shape was lost. Therefore, in order to reduce pit-like wrinkles, it is considered effective to reduce the propagation speed of cracks propagating through the base structure in addition to focusing on conventional carbide types and sizes. Was completed.
  • the casting temperature was 1450 ° C. to 1530 ° C., and the centrifugal force was such that the outer peripheral portion of the ring-shaped roll material had a gravity multiple of 180 G.
  • quenching and tempering were performed, and the hardness was HS 78-86.
  • the quenching treatment was performed by heating to a heating temperature of 1070 ° C. and air cooling. Further, the tempering treatment was performed twice or three times depending on the components at a temperature of 530 to 570 ° C. so that the amount of retained austenite was less than 10% by volume.
  • a hot-rolled fatigue test piece (outer diameter 60 mm ⁇ , wall thickness 10 mm) was taken from the obtained ring-shaped roll material, and the fatigue resistance of the hot rolling work roll in an actual machine was evaluated with good reproducibility in JP 2010-101752.
  • a hot rolling fatigue test was conducted to show that it was possible.
  • As the fatigue test piece a notch (depth t: 1.2 mm, circumferential length L: 0.8 mm) as shown in FIG. 1 was used at two locations on the outer peripheral surface, and a 0.2 mm ⁇ wire was used. It was introduced by the electric discharge machining (wire cut) method. Further, the end of the rolling surface of the fatigue test piece was chamfered with 1.2C.
  • the hot-rolling fatigue test was performed by a two-spindle rolling sliding method of a test piece having a notch (hot-rolling fatigue test piece) and a heated counterpart material. That is, as shown in FIG. 1, a test piece (hot rolled fatigue test piece) 1 was rotated at 700 rpm while being cooled with cooling water 2, and the rotating test piece 1 was heated to 800 ° C. by a high frequency induction heating coil 3. While the mating piece (material: S45C, outer diameter: 190 mm ⁇ , width: 15 mm) 4 was pressed with a load of 980 N, it was rolled at a slip ratio of 9%.
  • the structure of the obtained ring-shaped roll material was observed.
  • tissue observation a 10 ⁇ 10 ⁇ 5 mm (5 mm is the thickness direction of the ring) tissue observation specimen is taken at an arbitrary position within 10 mm from the outer surface of the ring-shaped roll material, and the 10 ⁇ 10 mm surface is a mirror surface Polishing was performed, and corrosion was performed with nital (5% by volume nitric acid + ethanol) for about 10 seconds.
  • a measurement test piece (5 mm ⁇ 10 mm ⁇ 5 mm) at an arbitrary position within 10 mm from the outer surface of the obtained ring-shaped roll material
  • the surface of 5 mm ⁇ 10 mm was mirror-polished and EBSD measurement was performed.
  • the measurement was performed by electron beam backscatter diffraction (EBSD) in an area of 10000 ⁇ m 2 or more at an acceleration voltage of 15 kV and a step size of 0.1 ⁇ m.
  • EBSD electron beam backscatter diffraction
  • a boundary line is drawn at a position where the azimuth difference between adjacent measurement points is 15 ° or more, and as shown in FIG. 12, the region surrounded by the boundary line is a single crystal, and the major axis is 5 ⁇ m or more on the measurement surface.
  • the minor axis of 20 crystals was measured and the average value was calculated.
  • FIG. 3 shows the relationship with + (% Ni)
  • FIG. 4 shows the relationship between the hot-rolled fatigue life and the minor axis of tempered martensite or bainite.
  • FIG. 3 shows that (% C ⁇ % V ⁇ 0.177 ⁇ % Nb ⁇ 0.129 ⁇ % Cr ⁇ 0.099 ⁇ % Mo ⁇ 0.063 ⁇ % W ⁇ 0.033) + (% Ni) is 0. It can be seen that when it is 0.05 or more or 4.0 or less, the hot-rolled fatigue life is remarkably improved.
  • V, Cr, Mo, Nb, and W are elements that are easy to produce carbides.
  • (% C-% V ⁇ 0.177-% Nb ⁇ 0.129-% Cr ⁇ 0.099-% Mo ⁇ 0 .063-% W ⁇ 0.033) represents the amount of carbon dissolved in the matrix.
  • the present invention has been completed based on the above findings, and the gist thereof is as follows.
  • C 2.0 to 3.0%
  • Si 0.2 to 1.0%
  • Mn 0.2 to 1.0%
  • Cr 4.0 to 7.0%
  • Mo 3.0 to 6.5%
  • V 5.0 to 7.5%
  • Nb 0.5 to 3.0%
  • Ni 0.05 to 3.0%
  • Co 0.2 -5.0%
  • W 0.5-5.0%
  • the contents of C, Cr, Mo, V, Nb, Ni, W satisfy the following formula (1)
  • the balance Fe and It has a composition consisting of inevitable impurities, and 85% or more of the base structure is a tempered martensite and / or bainite structure, and the minor axis of the tempered martensite or bainite is 0.5 to 3.0 ⁇ m.
  • Roll outer layer material for hot rolling 0.05 ⁇ (% C ⁇ % V ⁇ 0.177 ⁇ % Nb ⁇ 0.129 ⁇ % Cr ⁇ 0.099 ⁇ % Mo ⁇ 0.063 ⁇ % W ⁇ 0.033) + (% Ni) ⁇ 4 .0 (1)
  • % C,% V,% Nb,% Cr,% Mo,% W, and% Ni are the contents (mass%) of each element.
  • the present invention it is possible to manufacture a hot rolling roll outer layer material and a hot rolling composite roll in which the propagation speed of cracks is significantly reduced.
  • surface damage due to hot rolling such as rough skin and missing edges can be suppressed, and there is an effect that continuous rolling distance can be extended and roll life can be improved.
  • FIG. 1 shows the configuration of the testing machine used in the hot rolling fatigue test, the outer periphery of the hot rolling fatigue test specimen (fatigue test specimen), and the hot rolling fatigue test specimen (fatigue specimen) It is explanatory drawing which shows typically the shape and dimension of the notch introduced into the surface.
  • FIG. 2 is a diagram showing a result of measuring the outer layer material for hot rolling according to the embodiment of the present invention by EBSD.
  • FIG. 3 shows the hot-rolled fatigue life in the hot-rolled fatigue test and (% C-% V ⁇ 0.177-% Nb ⁇ 0.129-% Cr ⁇ 0.099-% Mo ⁇ 0.063-% W ⁇ 0 .033) + (% Ni).
  • FIG. 4 is a diagram showing the relationship between the hot-rolled fatigue life in the hot-rolled fatigue test and the minor axis of tempered martensite or bainite.
  • the roll outer layer material for hot rolling of the present invention is manufactured by a known casting method such as a centrifugal casting method or a continuous casting overlaying method, and can be used as it is as a ring roll or a sleeve roll, but for hot finish rolling. It is preferably used as an outer layer material of a composite roll for hot rolling.
  • the composite roll for hot rolling according to the present invention includes an outer layer and an inner layer welded and integrated with the outer layer.
  • An intermediate layer may be disposed between the outer layer and the inner layer. That is, instead of the inner layer welded and integrated with the outer layer, an intermediate layer welded and integrated with the outer layer and an inner layer welded and integrated with the intermediate layer may be used.
  • the composition of the inner layer and the intermediate layer is not particularly limited, but the inner layer is spheroidal graphite cast iron (ductile iron) or forged steel, and the intermediate layer is a high carbon material of C: 1.5 to 3.0% by mass. Is preferred.
  • C 2.0 to 3.0% C forms a solid solution to increase the base hardness and combines with a carbide forming element to form a hard carbide, thereby improving the wear resistance of the roll outer layer material.
  • the amount of eutectic carbide varies depending on the C content. Eutectic carbides affect the rolling service characteristics. For this reason, if the C content is less than 2.0%, the amount of eutectic carbide is insufficient, the frictional force during rolling increases, rolling becomes unstable, and the amount of C dissolved in the base structure is low. Reduces rolling fatigue resistance during heat resistance.
  • C is limited to a range of 2.0 to 3.0%.
  • the content is 2.1 to 2.8%.
  • Si 0.2 to 1.0%
  • Si is an element that acts as a deoxidizer and improves the castability of the molten metal.
  • a content of 0.2% or more is required.
  • Si is limited to 0.2 to 1.0%.
  • the content is 0.3 to 0.7%.
  • Mn 0.2 to 1.0%
  • Mn is an element having the effect of fixing S as MnS and detoxifying S, and partly dissolving in the base structure and improving the hardenability.
  • a content of 0.2% or more is required.
  • Mn is limited to 0.2 to 1.0%.
  • the content is 0.3 to 0.8%.
  • Cr 4.0 to 7.0% Cr combines with C to mainly form eutectic carbides, improves wear resistance, reduces friction with the steel sheet during rolling, reduces roll surface damage, and stabilizes rolling. It is an element having In order to obtain such an effect, the content of 4.0% or more is required. On the other hand, if the content exceeds 7.0%, coarse eutectic carbides increase, and fatigue resistance is lowered. For this reason, Cr is limited to the range of 4.0 to 7.0%. Preferably, the content is 4.3 to 6.5%.
  • Mo 3.0 to 6.5%
  • Mo is an element that combines with C to form a hard carbide and improves wear resistance.
  • Mo dissolves in hard MC-type carbides in which V, Nb, and C are bonded, strengthens the carbides, and also dissolves in eutectic carbides to increase the fracture resistance of these carbides. Through such an action, Mo improves the wear resistance and fatigue resistance of the outer roll layer material.
  • the content of 3.0% or more is required.
  • Mo-based hard and brittle carbides are produced, which reduces the rolling fatigue resistance during heat resistance and lowers the fatigue resistance. For this reason, Mo is limited to the range of 3.0 to 6.5%.
  • the content is 3.5 to 6.0%.
  • V 5.0-7.5%
  • V is an important element in the present invention in order to combine wear resistance and fatigue resistance as a roll.
  • V forms extremely hard carbide (MC type carbide), improves wear resistance, and effectively acts to sever and disperse eutectic carbide, thereby improving rolling fatigue resistance during heat resistance. Further, it is an element that remarkably improves fatigue resistance as a roll outer layer material. Such an effect becomes remarkable when the content is 5.0% or more.
  • the content exceeds 7.5%, the MC type carbides are coarsened, so that various properties of the rolling roll are made unstable. For this reason, V is limited to the range of 5.0 to 7.5%.
  • the content is 5.2 to 7.0%.
  • Nb 0.5 to 3.0%
  • Nb improves the wear resistance, particularly fatigue resistance, through the action of strengthening the MC type carbide by solid solution in the MC type carbide and increasing the fracture resistance of the MC type carbide.
  • Nb and Mo are dissolved in the carbide, the improvement in wear resistance and further fatigue resistance becomes significant.
  • Nb is an element which has the effect
  • Nb also has the effect of suppressing segregation during centrifugal casting of MC type carbide. Such an effect becomes remarkable when the content is 0.5% or more.
  • Nb is limited to a range of 0.5 to 3.0%.
  • the content is 0.8 to 1.5%.
  • Ni 0.05-3.0%
  • Ni is an element that dissolves in the matrix, lowers the transformation temperature of austenite during heat treatment, and improves the hardenability of the matrix. In order to acquire such an effect, 0.05% or more of content is required. On the other hand, if the content exceeds 3.0%, the transformation temperature of austenite becomes too low and the hardenability is improved, so that austenite tends to remain after heat treatment. When austenite remains, the rolling fatigue resistance during hot rolling is reduced, for example, cracks are generated during hot rolling. Therefore, Ni is limited to the range of 0.05 to 3.0%. Even if the cooling rate during the heat treatment is slow, it is preferably 0.2 to 3.0% from the viewpoint of ease of operation that the crystal size of the matrix structure can be made fine.
  • Co 0.2-5.0%
  • Co is an element that has a function of solid-dissolving in the matrix, strengthening the matrix, particularly at high temperatures, and improving fatigue resistance. In order to obtain such an effect, a content of 0.2% or more is required. On the other hand, even if the content exceeds 5.0%, the effect is saturated and an effect commensurate with the content cannot be expected, which is economically disadvantageous. Therefore, Co is limited to the range of 0.2 to 5.0%. Preferably, it is 0.5 to 3.0%.
  • W 0.5-5.0%
  • W is an element having a function of solid-dissolving in the matrix, strengthening the matrix at a high temperature and improving fatigue resistance, and forming M 2 C or M 6 C-based carbides, and wear resistance. To improve. In order to acquire such an effect, 0.5% or more of content is required. On the other hand, if the content exceeds 5.0%, not only the effect is saturated, but also coarse M 2 C or M 6 C-based carbides are formed, and the rolling fatigue resistance during heat resistance is reduced. For this reason, W is limited to a range of 0.5 to 5.0%. Preferably, it is 1.0 to 3.5%.
  • C, Cr, Mo, V, Nb, Ni, and W are contained in the above-described range, and further adjusted and contained so as to satisfy the following expression (1).
  • % C,% V,% Nb,% Cr,% Mo,% W, and% Ni are the contents (mass%) of each element.
  • V, Cr, Mo, Nb, and W are elements that are easy to produce carbides.
  • (% C-% V ⁇ 0.177-% Nb ⁇ 0.129-% Cr ⁇ 0.099-% Mo ⁇ 0.063- % W ⁇ 0.033) represents the amount of carbon dissolved in the base. Therefore, (% C-% V ⁇ 0.177-% Nb ⁇ 0.129-% Cr ⁇ 0.099-% Mo ⁇ 0.063-% W ⁇ 0.033) + (% Ni) It is the sum of the amount of dissolved carbon and the amount of Ni, and by adjusting this value to an appropriate range, a roll outer layer material having a slow crack propagation speed in the base and an excellent hot-rolled fatigue life can be obtained.
  • the balance other than the above components is composed of Fe and inevitable impurities.
  • the base structure is tempered martensite and / or bainite structure, and it is preferable that the minor axis of tempered martensite or bainite is 0.5 to 3.0 ⁇ m.
  • the base structure contains 85% or more of tempered martensite and / or bainite structure. It is more preferable that it is contained 90% or more from the viewpoint of property.
  • a retained austenite and / or pearlite are mentioned.
  • it may be controlled by repeating the cooling process after heating and holding at 500 to 570 ° C.
  • the minor axis of tempered martensite or bainite in a component system in which the minor axis of tempered martensite or bainite is smaller than 0.5 ⁇ m, the transformation temperature becomes too low, and it becomes difficult to reduce the amount of retained austenite even if tempering is repeated. Cracking during hot rolling due to austenite may occur, and the hot rolling fatigue resistance is reduced.
  • the minor axis of tempered martensite or bainite exceeds 3.0 ⁇ m, the crack propagation rate of the base structure is high, and the rolling fatigue resistance during heat resistance decreases. Therefore, it is preferable to limit the minor axis of tempered martensite or bainite of the base structure to a range of 0.5 to 3.0 ⁇ m.
  • the thickness is preferably in the range of 0.5 to 2.0 ⁇ m.
  • the components and the cooling rate may be controlled so that the transformation temperature of the matrix is in the range of 200 to 400 ° C.
  • the roll outer layer material is preferably produced by a known centrifugal casting method or a casting method such as a continuous casting overlay method. Needless to say, the present invention is not limited to these methods.
  • a molten mold having the above-described roll outer layer material composition is applied to a rotating mold whose inner surface is coated with a refractory material mainly composed of zircon or the like in a thickness of 1 to 5 mm. It is poured and centrifugally cast so as to have a predetermined thickness.
  • the number of rotations of the mold is preferably in the range of 120 to 220 G in the gravity multiple applied to the outer surface of the roll.
  • the mold rotation and stand the mold After the outer layer or the intermediate layer is completely solidified, it is preferable to stop the mold rotation and stand the mold, and then statically cast the inner layer material to form a composite roll. Thereby, the inner surface side of the roll outer layer material is redissolved to form a composite roll in which the outer layer and the inner layer, or the outer layer and the intermediate layer, and the intermediate layer and the inner layer are welded and integrated.
  • the inner layer it is preferable to use spheroidal graphite cast iron, worm-like graphite cast iron (CV cast iron), etc. excellent in castability and mechanical properties for the inner layer to be statically cast.
  • the outer layer and the inner layer are integrally welded, so that the component of the outer layer material is mixed in the inner layer by about 1 to 8%.
  • carbide forming elements such as Cr and V contained in the outer layer material are mixed into the inner layer, the inner layer is weakened. For this reason, it is preferable to suppress the mixing rate of the outer layer component into the inner layer to less than 6%.
  • the intermediate layer when forming the intermediate layer, it is preferable to use graphite steel, high carbon steel, hypoeutectic cast iron or the like as the intermediate layer material.
  • the intermediate layer and the outer layer are integrally welded in the same manner, and the outer layer component is mixed in the intermediate layer in the range of 10 to 95%. From the viewpoint of suppressing the amount of the outer layer component mixed into the inner layer, it is important to reduce the amount of the outer layer component mixed into the intermediate layer as much as possible.
  • the composite roll for hot rolling of the present invention is preferably subjected to heat treatment after casting.
  • heat treatment it is preferable to perform the step of heating to 950 to 1100 ° C. by air cooling or blast air cooling, and further the step of cooling after heating and holding at 500 to 570 ° C. is performed twice or more.
  • the cooling rate in accordance with the components so that the transformation temperature is in the range of 200 to 400 ° C., it is possible to obtain the above-mentioned preferred minor axis size.
  • the amount of tempered martensite and / or bainite in the base structure changes depending on the number of repetitions of the cooling step after heating and holding at 500 to 570 ° C., 85% or more of the base structure is tempered martensite and / or Alternatively, the number of repetitions may be set so as to be bainite.
  • the preferred hardness of the composite roll for hot rolling of the present invention is 79 to 88 HS (Shore hardness), and more preferred is 80 to 86 HS. If the hardness is lower than 80 HS, the wear resistance is deteriorated. Conversely, if the hardness exceeds 86 HS, cracks formed on the surface of the hot rolling roll during hot rolling are difficult to remove by grinding. It is preferable to adjust the heat treatment temperature and heat treatment time after casting so that such hardness can be stably secured.
  • the melt of the roll outer layer material composition shown in Table 1 was melted in a high-frequency induction furnace and made into a ring-shaped test material (ring roll; outer diameter: 250 mm ⁇ , width: 65 mm, wall thickness: 55 mm) by centrifugal casting.
  • the casting temperature was 1450 to 1530 ° C., and the centrifugal force was such that the outer peripheral portion of the ring-shaped roll material was 180 G in the multiple of gravity.
  • the quenching temperature is reheated to 1070 ° C., air-cooled, and quenching quenching and tempering are performed at a temperature of 530 to 570 ° C. so that the residual austenite amount is less than 10% by volume.
  • Vickers hardness HV50 is measured with a Vickers hardness tester (test force: 50 kgf (490 N)) in accordance with the provisions of JIS Z 2244, and Shore hardness HS is calculated with a JIS conversion table. Converted. The measurement points were 10 points each, the maximum value and the minimum value were deleted, the average value was calculated, and the hardness of the test material.
  • the hot rolling fatigue test method was as follows. A hot rolling fatigue test piece (outer diameter 60 mm ⁇ , wall thickness 10 mm, chamfered) was collected from the obtained ring-shaped test material. In the hot rolling fatigue test piece, notches (depth t: 1.2 mm, circumferential length L: 0.8 mm) as shown in FIG. 1 are provided at two locations on the outer peripheral surface (positions 180 ° apart). And introduced by an electric discharge machining (wire cut) method using a 0.20 mm ⁇ wire. As shown in FIG. 1, the hot rolling fatigue test was performed by a two-disk sliding rolling method between a test piece and a counterpart material.
  • the test piece 1 was rotated at 700 rpm while being cooled with cooling water 2, and the rotating test piece 1 was heated to 800 ° C. with the high frequency induction heating coil 3 (material: S45C, outer diameter: 190 mm ⁇ , width: 15 mm). , C1 chamfer) 4 was brought into contact with a load of 980 N while rolling at a slip ratio of 9%. And it rolled until the two notches 5 introduced into the hot rolling fatigue test piece 1 broke, each rolling rotation speed until each notch broke was calculated
  • tissue observation a 10 ⁇ 10 ⁇ 5 mm (5 mm is the thickness direction of the ring) tissue observation specimen is taken at an arbitrary position within 10 mm from the outer surface of the ring-shaped roll material, and the 10 ⁇ 10 mm surface is a mirror surface Polishing was performed, and corrosion was performed with nital (5% by volume nitric acid + ethanol) for about 10 seconds.
  • the short diameter (short axis length) of tempered martensite or bainite is obtained by taking an EBSD measurement test piece (5 mm ⁇ 10 mm ⁇ 5 mm) from an arbitrary position within 10 mm from the outer surface of the obtained ring-shaped roll material, A surface of 5 mm ⁇ 10 mm was mirror-polished and determined by EBSD measurement. EBSD measurement was performed in an area of 10000 ⁇ m 2 or more at an acceleration voltage of 15 kV and a step size of 0.1 ⁇ m. Using the obtained data, as shown in FIG.
  • a boundary line is drawn at a position where the azimuth difference between adjacent measurement points is 15 ° or more, and the region surrounded by the boundary line is taken as one crystal, and the measurement surface Above, the minor axis of 20 crystals whose major axis is 10 ⁇ m or more was measured, and the average value was calculated.
  • the hot-rolled fatigue life was remarkably increased, and an excellent hot-rolled fatigue life exceeding 350,000 times was exhibited.
  • the structure observation it was confirmed that 85% or more of the base structure was tempered martensite and / or bainite structure.
  • the present invention it is possible to manufacture a composite roll for hot rolling in which the propagation speed of cracks is significantly reduced. As a result, surface damage due to hot rolling such as rough skin and missing edges can be suppressed, so that the effect of extending the continuous rolling distance and improving the roll life can also be obtained.
  • Test piece hot rolled fatigue test piece
  • Cooling water High frequency induction heating coil 4
  • Opposite piece 5 Notch

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Reduction Rolling/Reduction Stand/Operation Of Reduction Machine (AREA)
  • Heat Treatment Of Articles (AREA)
PCT/JP2017/023663 2016-09-07 2017-06-28 熱間圧延用ロール外層材および熱間圧延用複合ロール WO2018047444A1 (ja)

Priority Applications (5)

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BR112019003360A BR112019003360A2 (pt) 2016-09-07 2017-06-28 material de camada externa de cilindro de laminação a quente e cilindro compósito para laminação a quente
EP17848389.7A EP3479915B1 (en) 2016-09-07 2017-06-28 Roll outer layer material for hot rolling and composite roll for hot rolling
KR1020197004864A KR102234330B1 (ko) 2016-09-07 2017-06-28 열간 압연용 롤 외층재 및 열간 압연용 복합 롤
CN201780050783.6A CN109641250B (zh) 2016-09-07 2017-06-28 热轧用辊外层材料及热轧用复合辊
JP2017552525A JP6292362B1 (ja) 2016-09-07 2017-06-28 熱間圧延用ロール外層材および熱間圧延用複合ロール

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JP2020022989A (ja) * 2018-08-08 2020-02-13 日立金属株式会社 圧延用遠心鋳造複合ロールの外層材、及び圧延用遠心鋳造複合ロール
JP7400771B2 (ja) 2021-05-20 2023-12-19 Ｊｆｅスチール株式会社 熱間圧延用ロール外層材および熱間圧延用複合ロール

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JP7063180B2 (ja) 2018-08-08 2022-05-09 日立金属株式会社 圧延用遠心鋳造複合ロールの外層材、及び圧延用遠心鋳造複合ロール
JP7400771B2 (ja) 2021-05-20 2023-12-19 Ｊｆｅスチール株式会社 熱間圧延用ロール外層材および熱間圧延用複合ロール

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TWI655295B (zh) 2019-04-01
BR112019003360A2 (pt) 2019-06-04
TW201812028A (zh) 2018-04-01
EP3479915B1 (en) 2021-07-21
EP3479915A1 (en) 2019-05-08
KR102234330B1 (ko) 2021-03-30
JPWO2018047444A1 (ja) 2018-09-06
KR20190029716A (ko) 2019-03-20
JP6292362B1 (ja) 2018-03-14
CN109641250A (zh) 2019-04-16
CN109641250B (zh) 2020-11-03

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